DE3586669T2 - METHOD AND DEVICE FOR THE COAXIAL EXTRACTION OF PASTE OF DUGS WITH PARTICLES IN THE EXTERNAL SURFACES. - Google Patents

Abstract

A continuous co-extruded food product is formed having dissimilar inner and outer portions wherein the inner portion is enveloped by the outer portion and the outer portion is a dough containing particulate material such as chocolate chips. The product is formed by an inner extrusion port being recessed a distance d from an outer extrusion port with the distance d being sufficient for permitting particulate material in the outer dough portion to pass through an exit passage. between the inner and outer extrusion ports without clogging or agglomeration. Turbulence is induced in the outer dough portion which envelops the inner portion thereby causing the particulate material to tumble whereby at least a portion of the particulate material partially penetrates the exterior surface of the outer dough portion enveloping the inner portion. Dough is removed from the surface of the part of the particulate material penetrating the exterior surface of the outer dough portion. In a preferred embodiment, the outer extrusion port includes a land surface generally parallel to the axis of the outer extrusion port and a bevel surface at the interior surface of the outer extrusion port. The land surface intersects the beveled surface at a generally sharp line of intersection. The generally sharp line of intersection and the bevel surface cause the tumbling of the particulate material. The land surface removes dough from the surface of the particulate material which penetrates the exterior surface of the outer dough portion.

Description

The present invention relates to the production of edible products with unequal inner and outer portions. In particular, the present invention is directed to the production of food products in which an inner portion is covered by an outer dough portion and the outer dough portion contains finely divided substance.

Background of the invention

The types of products covered by the present invention include baked goods baked from dough pieces having an outer layer of farinaceous dough and a core which may be a dissimilar dough or other material such as a jam, cream, puree, or other extrudable form of fruit, cheese, meat, vegetable, confection, or other "edible" substance. In those products where the core is also of dough, the outer and inner doughs would advantageously be dissimilar in composition to produce different flavors, colors, appearances, textures, consistencies, or the like in the inner and outer portions of the baked product. Regardless of the composition of the inner and outer portions, the present invention is directed to products containing particulate substances such as chocolate chips, candied fruit, nuts, raisins, and the like in the outer portions thereof.

In the past, products with inner and outer portions have been developed by concentrically extruding an extrudate strand, as shown in U.S. Patent No. 3,572,259 to Hayashi.

An automatic machine for making filled baked goods is described in U.S. Patent No. 3,196,810 to Roth. In this patent, a plurality of nozzles introduce flavoring materials into a dough. U.S. Patent No. 3,778,209 to Wallace et al. describes an apparatus for making an extruded food product in which an inner meat food product is completely encased in an outer deformable food product, using a coaxial nozzle and a pair of augers for forcing food products, from a respective pair of food hoppers, through the coaxial nozzle. Augers are particularly useful for extruding food products, such as dough, to facilitate the high speed production of snack foods, such as cookies, chocolate-coated To achieve consistent quality, reliability and high efficiency in the production of food and similar products.

In the manufacture of coaxially extruded food substances, it is usually required that the outer food substance enclose or envelop an inner food substance. In U.S. Patent Nos. 3,778,209 to Wallace et al. and 3,249,068 to Gembicki, the enveloping process is accomplished by controlling the movement of a plunger used in conjunction with feeding the food material for enclosing. In U.S. Patent No. 4,251,201 to Krysiak, a coated piece of food is produced by means of an apparatus that includes specially sequenced feed mechanisms used to coaxially extrude an inner and outer food product from coaxial dies in combination with a sequenced, orifice-shaped closure valve that is tightly mounted to the discharge orifices of the extrusion dies. The orifice valve terminates coaxial extrusion at the time when the feed of each of the inner filler and outer coating sutures is interrupted and the space in which the valve operates is filled with the outer coating food. This technique appears to depend on a relatively easy flow of the outer food substance to coat the back of the inner food as the iris valve begins to close and appears to be limited in terms of operating speed because the feeding of both the inner and outer food must be interrupted for each piece of food produced.

Recently, relatively high speed methods and devices have been developed in which an inner dough coaxially extruded with an outer dough is enclosed by severing the outer dough with a blunt severing edge or severing element which simultaneously draws the outer dough on both sides of a severed element over the inner dough to form a fully encased food piece. See for example our European patent application EP-A-130772.

In all of the known processes discussed above, there is no disclosure of entrapping finely divided substances in the outer portion of the dough. Consequently, none of the references discloses any process or apparatus that facilitates the entrapping of finely divided substances in the outer portion of a coaxially extruded dough strand.

Experience with the coaxial extrusion technique has taught that certain difficulties are encountered when extruding an outer tube of a doughy mass containing finely divided substance. For example, the normal configuration of the die head is such that the annular space between the outside perimeter of the inner extrusion orifice and the inside of the outer extrusion orifice prevents smooth passage of the finely divided substance. In some cases, the space is simply too narrow to allow passage of the particles when adjusted to provide the appropriate flow proportion and tube thickness. Another problem encountered is agglomeration of particles as they enter the exit passage, blocking the extrusion flow or causing an irregular dough outer tube.

When it is desired to extrude a particulate-containing dough outer tube to produce an attractive, relatively smooth-covered confection or cake in which the particulate matter appears to be externally introduced or hand-made, the problems are magnified. The particulates are desirably free from partial coverage by the dough. This improves the appearance of the finished product, which is an important commercial consideration. To improve the appearance of the product, the particulates should penetrate through the external surface of the dough outer and be free from partial coverage by the dough.

Another consideration relating to the extrusion of an outer tube of a doughy mass with particles is that the integrity of the outer dough portion should be maintained, especially in the case of a coaxially extruded cake dough, so that the final product appears entirely hand-made. Any discontinuity through which the inner portion can be seen undermines the appearance of the product as being hand-made.

Furthermore, it would be desirable that each of the above issues be resolved while maintaining high-speed manufacturing.

We have now been able to overcome the problems previously mentioned regarding the extrusion of a dual-material dough mass having an inner and an outer portion, wherein the outer portion contains finely divided material. Thus, we have been able to provide a method and apparatus for the coaxial extrusion of an inner dough mass and an outer dough mass containing finely divided material, wherein at least a portion of the particles in the outer dough mass penetrate the outer surface of the outer doughy mass and all partial coverage of the finely divided material penetrating the outer surface of the outer doughy mass by dough is substantially eliminated.

It has now further become possible for us to provide a method and apparatus for the manufacture of cake products comprising a dissimilar inner dough and an outer dough with chocolate chips by coaxially extruding the inner dough and a chocolate chip-containing outer dough wherein the chocolate chips penetrate the outer surface of the outer dough and the resulting chocolate chip cake product has a commercially desirable handmade appearance.

Summary of the invention

One aspect of the apparatus of the present invention is that the inner extrusion opening is recessed from the outer extrusion opening to define an exit passage. This aspect has already been proposed in Austrian patent specification AT-B-293,976 which describes an apparatus for coaxial extrusion to form a continuous food product having unequal inner and outer portions, in which the inner portion is encased in the outer portion and the outer portion is a dough containing finely divided material consisting of particles, the apparatus comprising:

an inner extrusion opening having an exit opening with a first cross-sectional area, through which the inner portion is extrudable;

an outer extrusion orifice having an exit opening having a second cross-sectional area greater than the first cross-sectional area; the inner extrusion orifice being recessed from the outer extrusion orifice, the recessed distance (d) forming an exit passageway between the inner extrusion orifice and the outer extrusion orifice; and the outer extrusion orifice having a generally annular bevel surface with means for substantially removing dough from the portions of particles passing through the outer surface of the outer dough portion which are aligned substantially parallel to the axis of the outer extrusion orifice, the bevel surface terminating on the inside of the outer extrusion orifice in a generally sharp intersection with the inner surface of the outer extrusion orifice, the generally sharp intersection providing means for introducing turbulence into the outer dough portion which envelops the inner portion

first conduit means communicating with the inner extrusion opening for conveying the inner portion thereto; and

second conduit means communicating with the outlet passage for conveying the outer dough portion thereto;

According to the present invention, such a device is characterized in that the arrangement is such that the finely divided material in the outer dough portion is rolled by the turbulence introducing means and a part of at least a portion of the particles of the finely divided material passes through the outer surface of the outer dough portion and the distance (d) is suitably adapted such that the particles of the finely divided material present in the dough of the outer portion can pass through the exit passage during operation of the device; and arcuate cutouts are provided on the phase surface and are aligned substantially parallel to the axis of the outer extrusion opening.

The inner extrusion opening is recessed from the outer extrusion opening by a sufficient distance to permit the passage of the outer dough containing finely divided material therethrough without agglomeration of the particles. This distance is suitably at least about 1.25 times the maximum amount of finely divided material in the outer dough mass.

In one embodiment, the turbulence inducing means includes a generally annular beveled edge on the inside of the opening of the outer extrusion orifice, adjacent a generally annular bevel surface that is generally parallel to the axis of the outer extrusion orifice. The annular beveled edge abuts the annular bevel surface at a substantially sharp intersection. The generally annular bevel surface has a length sufficient to remove dough coatings from the portions of particles that pass through the outer surface of the outer dough portion. Preferably, the angle of the beveled edge is between about 15° and about 60°, while the annular bevel surface has a length of from about 1/16 inch (1.6 mm) to about 5/16 inch (7.9 mm) and a length of about 3/16 inch (4.8 mm).

The present invention also provides a method of coaxial extrusion for forming a continuous food product having unequal inner and outer portions, the inner portion being enveloped in intimate contact by the outer portion and the outer portion being a dough material, the method comprising:

Providing finely divided material consisting of particles in the outer portion of dough material;

Extruding the inner portion through an inner extrusion opening;

passing the outer portion of dough material containing finely divided material through an exit passage formed by recessing the inner extrusion opening a distance (d) from an outer extrusion opening, the distance (d) being sufficient to allow the particles of finely divided material contained in the outer portion of dough material to pass through the exit passage, the outer portion of dough material enveloping the inner portion;

Passing the inner portion, which is encased in the outer portion of dough material, through the outer extrusion opening, thereby forming a composite, strand-like food product which has the outer portion of dough material in intimate contact with the has an inner portion;

creating turbulence in the outer portion of dough material surrounding the inner portion, causing at least a portion of the particles to roll and partially pass through the outer surface of the outer portion of dough material before the composite strand-like food product exits the outer extrusion orifice; and

Removing dough from the portion of the particles which pass through the outer surface of the outer portion of dough material before the assembled strand-like food product exits the outer stranding orifice.

In a preferred embodiment of the present invention, the outer dough portion is a chocolate chip cake batter containing chocolate chips as a finely divided material. The inner doughy mass is a non-uniform chocolate chip cake batter which may include a humectant so that the batter remains moist and juicy even after baking. If desired, the inner doughy mass may also contain chocolate chips to enhance the flavor and sweetness of the inner dough.

Using the present invention, it is possible to produce a coaxially extruded dough strand which has a smooth overall appearance without any discontinuity or imperfections through which the inner doughy mass can be seen and in which there is no partial covering or "skin" of dough mass over the particles which have passed through the outer surface of the outer dough portion.

The present invention can be easily adapted for high speed process use without extensive modifications to existing equipment.

Short description of the drawings

in the drawings, which illustrate preferred embodiments of the invention,

Fig. 1 is a schematic side view, partially in cross section, of an embodiment of a coaxial extrusion apparatus according to the present invention;

Fig. 2 is a simplified schematic cross-sectional view of a similar embodiment of a coaxial extrusion apparatus according to the present invention to that illustrated in Fig. 1;

Fig. 3 is a simplified schematic cross-sectional view similar to Fig. 2, further illustrating an inner doughy mass and an outer doughy mass containing finely divided material;

Fig. 4 is a simplified schematic illustration of an alternative embodiment an outer extrusion opening which can be used with the device of Fig. 1; and

Fig. 5 is a schematic side view similar to Fig. 1, partially in cross-section, further showing an inner doughy mass and an outer doughy mass containing finely divided material and the operation according to an embodiment of the present invention.

Description of the preferred embodiments

In order to ensure a better understanding of the present invention and a recognition of its advantages, a detailed description of preferred embodiments is presented below.

Fig. 1 is a schematic representation of a coaxial extrusion apparatus 5 according to the present invention. The coaxial extrusion apparatus 5 comprises a die shell 7 and an inner filler tube or inner extrusion conduit 10. The end of the inner extrusion opening 10 terminates with the inner extrusion opening 11. The inner filler tube or inner extrusion conduit 10 surrounds the outer extrusion conduit 23 which is bounded by the outer wall of the inner extrusion conduit 10 and the wall 29 of the die shell 7. Located on the underside of the die shell 7 and below the inner extrusion opening is the extrusion die base 20 in which the outer extrusion opening 21 is located. Below the outer extrusion opening 21, conveyor means 30 is located for receiving and transporting the coaxially extruded doughy strand, for example to an oven.

Apparatus for producing food products having unequal inner and outer portions by coaxial extrusion through concentric inner and outer extrusion dies or conduits are well known in themselves and do not require detailed discussion. Examples of prior art apparatus are shown in the prior art patents discussed above.

According to conventional designs, an inner doughy mass would be fed via conduit means from a first hopper into the inner extrusion line or filler tube 10 by conventional means (not shown). Similarly, an outer doughy mass would be fed via conduit means from a second hopper into the outer extrusion line 23 by conventional means (not shown). Means for feeding the inner doughy mass into the filler tube 10 and the outer doughy mass into the outer extrusion line 23 may be, for example, well-known drilling devices. Feeding the doughy masses through the extrusion lines may also be carried out by suitable gas pressure. The manner and means of feeding doughy masses into inner and External coaxial extrusions are well known in the art and are not part of the present invention. Therefore, they are not discussed in detail here.

Conduit means 31 and conduit means 37 are illustrated in Fig. 1 and represent means for feeding the inner doughy masses into the filler tube 10 and the outer doughy mass into the outer extrusion conduit 23, respectively. As illustrated in Fig. 1, the outer extrusion conduit 23 is of a larger size on the right hand side of the figure where the outer doughy mass is fed into the outer extrusion conduit. The outer doughy mass surrounds the inner filler tube 10 and is forced through the exit passage 28 between the inner extrusion orifice 11 and the die base 20, the outer doughy mass surrounding and enveloping the inner doughy mass extruded through the inner extrusion orifice 11. The composite outer doughy mass enveloping the inner doughy mass is forced or extruded through the outer extrusion opening 21 of the extrusion die 20. The general arrangement of such coaxial extrusion devices is well known in the art.

The inner filler tube 10 and the inner extrusion orifice 11 may assume a variety of geometric cross-sections. Suitably, the geometric cross-section of the filler tube 10 and the inner extrusion orifice 11 is circular. Likewise, the annular outer extrusion orifice 23 and the outer extrusion orifice 21 may assume a variety of geometric cross-sections. Suitably, the outer extrusion orifice 21 has a circular cross-section. The extent of the cross-sectional area of the outer extrusion orifice 21 is greater than the extent of the cross-section of the inner extrusion orifice 11 to allow the outer doughy mass to envelop the inner doughy mass to create the coaxially extruded strand-like product having unequal outer and inner portions in accordance with the well-known manner in the art.

As shown in Fig. 1, the left boundary surface of the inner extrusion opening 11 is arranged in approximate axiality to the left bevel surface 24 of the outer extrusion opening 21 of the lower die base 20. It is found that such axiality is advantageous for the production of a satisfactory product when the coaxially extruded strand-like product with unequal outer and inner portions is picked up by a conveyor 30 moving to the right and transported away as indicated by the arrow A in Fig. 1. That is, the best results in terms of the quality of the coaxially extruded product cannot generally be achieved by arranging the inner extrusion opening 11 concentrically with respect to the outer extrusion opening 21 when the conveyor 30 moves as indicated by the arrow The precise lateral location of the inner extrusion orifice 11 with respect to the outer extrusion orifice 21 to produce a high quality product may vary slightly depending upon the composition of the inner and outer doughy masses and the linear speed of the conveyor 30, but may be routinely determined in view of the foregoing general control. Means (not illustrated) for moving the die shell 7 and thereby the outer extrusion orifice 21 laterally with respect to the inner extrusion orifice 11 would be provided.

According to the present invention, finely divided materials, such as chocolate chips, are distributed in the outer dough mass which is driven through the outer extrusion line 23. According to the present invention, means are provided for rolling the finely divided material of the outer dough mass which envelops the inner dough mass so that at least a portion of the finely divided material passes through the outer surface of the outer dough mass portion of the coaxially extruded strand-like product formed of unequal inner and outer portions. Further, according to the present invention, means are provided whereby partial coverage of the particles which pass through the outer surface of the coaxially extruded product is removed.

The method and apparatus of the present invention will now be explained in more detail with reference to Figures 1 and 2, Figure 2 being a schematic detail of the filler tube 10 and the lower die plate 20. Reference is also made to Figure 3, which is similar to Figure 2 and which schematically illustrates the coaxial extrusion of inner doughy mass 34 and outer doughy mass 32 containing finely divided material 26, whereby a coaxially extruded strand-like product of unequal inner dough 34 and outer dough 32 is formed and a portion of the finely divided material 26 passes through the outer surface 33 of the outer dough 32 of the strand-like product 35. In Figures 2 and 3, for clarity of illustration, the inner extrusion opening 11 is generally concentric with the outer extrusion opening. However, as already discussed previously, such an arrangement of the inner extrusion opening 11 in relation to the outer extrusion opening 21 is not always optimal for all operating modes.

The outer extrusion opening 21 having an opening 25 is formed in the lower die base 20 and includes an annular chamfer surface 24 and an annular bevel surface 22 on the inside of the outer extrusion opening 21. The annular chamfer surface 24 intersects the annular bevel surface or edge 22 at point 27, thereby forming an annular intersection line. The annular chamfer surface 24 is a peripheral surface of the outer Extrusion opening 21 and parallel to the axis of the outer extrusion opening 21. The bevel surface 22 is located within the outer extrusion opening inner side 21 (ie the side of the outer extrusion opening 21 which is opposite the inner extrusion opening 11). The bevel surface 22 extends around the outer boundary of the outer extrusion opening 21. The bevel or surface 22 is formed at an angle to a line perpendicular to the axis of the outer extrusion opening 21 and thereby to the surface of the bevel surface 24.

The turbulence introducing means according to the present invention includes the bevel edge or surface 22 and the intersection line 27 between the bevel edge 22 and the bevel surface 24. It is important that the intersection line 27 between the bevel edge 22 and the bevel surface 24 be substantially sharp. This substantially sharp intersection point 27 is particularly effective for introducing turbulence into the finely divided substance 26 of the outer dough 32.

By "substantially sharp" is meant that the cutting line 27 is permitted to have a very small radius. A very small radius might be desirable from a practical point of view, for example to prevent an operator from cutting himself when handling the device. A sharp cutting line (i.e., not having even a small radius) would, on the other hand, provide entirely satisfactory performance. However, it is important that there is not a large radius at the intersection between bevel 27 and the annular bevel surfaces 24. A large radius would not result in the desired creation of turbulence in the outer dough 32, and the rolling of the finely divided material 26 and thereby the subsequent satisfactory passage through the outer surface 33 of the composite strand-like product 35 would not be achieved.

The bevel surface 24 having a length parallel to the axis of the outer extrusion opening 21 serves to remove, caused by the cut line 27, partial dough covering or dough skin from the fine particle material 26 which passes through the outer dough surface of the outer dough due to the rolling of the fine particle material 26. The length of the bevel surface 24 must be sufficient to substantially remove any partial dough covering or skin from the fine particle material 26 which passes through the outer dough surface 33 of the outer dough. However, if the length of the bevel surface 24 is too long, it could have the effect of forcing the fine particle material 26 which has passed through the outer dough surface 33 back into the dough.

According to the present invention, the inner extrusion opening 11 of the filler tube 10 is recessed by a distance from the outer extrusion opening 21. The recessing of the inner Extrusion opening 11 is spaced a distance from the outer extrusion opening 21 to define an exit passage 28 through which the doughy mass containing finely divided material 26 passes as it begins to envelop the inner doughy mass 34 emerging from the inner extrusion opening 11. The distance is selected to be sufficient to permit the passage of the particles of finely divided material 26 contained in the outer dough 32 through the exit passage 28 without clogging or buildup.

Advantageously, the spacing is selected to be at least about 1.25 times the maximum dimension of the largest particle 26 disposed in the outer doughy mass 32 to prevent sticking or clogging of the finely divided material 26 in the exit passage 28. In most applications, more than about 2 would not be achieved because if larger, in most cases the cross-sectional area of the opening 25 of the outer extrusion orifice 21 would tend to grow rapidly and the thickness of the outer doughy mass 32 would tend to become large relative to the thickness of the inner doughy mass 34 of the strand-like coaxially extruded product 35 and thereby not result in what is usually considered a desirable commercial product. It will now be understood that the spacing is not defined by accidental very large particles which do not conform to the intended commercial particle size or nature. Generally, the closest distance from the inner extrusion opening 11 to the outer extrusion opening 21 is about 5/16 inch (7.9 mm) to about 7/16 inch (11.1 mm), with 5/16 inch (7.9 mm) being satisfactory in many applications.

The chamfer surface 24 may be circular with a constant diameter and a smooth surface. When the chamfer surface 24 is circular, suitable diameters for the opening of the outer extrusion orifice 25 range from about 11/16 inch (17.5 mm) to about 1-1/8 inch (28.6 mm). The inner extrusion port opening is suitably of circular cross-section with a diameter of from about 9/16 inch (14.3 mm) to about 1 inch (25.4 mm). The cross-sectional area of the outer extrusion port opening 21 would be larger than the cross-sectional area of the inner extrusion port opening 11. Good results have been obtained when the outer extrusion port opening has a diameter of 27/32 inch (21.4 mm) and the inner extrusion port opening has a diameter of 5/8 inch (15.9 mm). As previously discussed herein, the inner extrusion port 11 and the outer extrusion port 21 need not have a circular or annular cross-section. Other cross-sectional shapes having a closed outer perimeter can give satisfactory results and this refers here to the substantially annular.

The angle of the beveled edge 22 is generally greater than about 15°. Very satisfactory results have been obtained with a 60° angle. Suitable lengths for the bevel surface 24 parallel to the axis of the outer extrusion orifice 21 (i.e., dimension of Fig. 2) are from about 1/16 inch (1.6 mm) to about 5/16 inch (7.9 mm), with a length of about 1/8 inch (3.2 mm) being found satisfactory.

The lower die plate 20 with the outer extrusion orifice 21 formed therein may be made of a single molded or machined material as illustrated in Fig. 2 or it may be made of an inner plate having a beveled edge or surface 22 bonded in combination with an outer plate of the same or different material which provides the annular beveled surface 24 as illustrated in Fig. 3. In either case the sharp or substantially sharp cutting line 27 will lie between the beveled edge 22 and the beveled surface 24.

As illustrated in Fig. 4, the bevel surface 24 of the outer extrusion orifice 21 may be provided with elongated arches 37, i.e., arches extending in the direction of the axis of the outer extrusion orifice 21. If used, the arches would be of a size such as to prevent the total ingress of particles of the finely divided material 26 disposed in the outer doughy mass 32.

The operation of the present invention can be described in connection with Figures 3 and 5. An inner dough 34 is fed under pressure through a filler tube or inner extrusion line 10 by means previously discussed herein, such as a stagger or gas pressure. An outer dough 32, which is not like the inner dough 34, is fed under pressure through an outer extrusion line 23. In accordance with the present invention, the outer dough 32 contains particulate material 26. The inner dough 34 exits the inner extrusion orifice 11 and is enveloped by the outer dough 32 which exits the annular exit passage 28. The inner dough 34, encased in the outer dough 32, passes through the outer extrusion opening 21. The finely divided material 26 in the outer dough 32 is caused to roll as the outer dough passes over the bevel 22 and the substantially sharp cutting line 27. The substantially sharp cutting edge 27 is particularly important in the described embodiment for causing the finely divided material 26 to roll, or in other words, for introducing turbulence into the outer doughy mass whereby the finely divided material 26 rolls.

At least a small portion of the particles of the finely divided material 26, which has been caused to roll by the turbulence-inducing means, is passed through the outer surface 33 of the outer doughy mass 32 as the product coaxially extruded from the inner doughy mass 34 and the outer doughy mass 32 passes through the bevel surface 24. The bevel surface 24 substantially partially removes dough coverings or skins from the finely divided substance 26 which has passed through the outer surface 33 of the outer doughy mass 32. It will be appreciated that a portion of the finely divided material 26 remains embedded in the outer doughy mass 32. However, a sufficient amount of particles of the finely divided material 26 will be rolled at or near the surface of the outer doughy mass to impart the desired appearance to the extruded strand-like dough product 35.

The assembled doughy strand-like product 35 exits the outer extrusion opening 21 and is received and transported by a horizontally disposed conveyor 30. Typically, the assembled doughy strand-like product 35 would be cut into individual pieces on the conveyor 30 by any convenient cutting means well known in the art. The cut pieces of the strand-like product would be further transported to an oven for baking.

The operation of the apparatus and method of the present invention would most advantageously be carried out continuously in an automated process. The composite doughy rope-like product 35 can be extruded at a low speed level of about 2 feet/minute (61 cm/min.) and the desired rolling effect is achieved. The maximum speed of extruding the rope-like product 35 could typically be 35 feet/minute (10.67 m/min.). The maximum speed of extrusion of the strand-like product 35 is determined by practical considerations such as the size of the oven and the avoidance of cracks in the outer dough 32 of the composite strand-like product 35. Generally, the conveyor 30 receives the coaxially extruded composite strand-like dough product 35 and conveys it away at a speed equal to or only slightly higher than the extrusion speed so that the strand-like product 35 is aligned in the direction of movement of the conveyor 30, but not so excessively stretched as to cause invisible discontinuities in the outer dough portion.

The method and apparatus of the present invention can be readily adapted for use on many coaxial extrusion machines for producing food products with unequal inner and outer portions.

The apparatus and method of the present invention are highly advantageous for the automated manufacture of chocolate chip cakes having unequal inner and outer doughs and wherein the finished product has a commercially desirable hand-made appearance. According to a preferred embodiment of the present invention, the inner dough 34 would be a chocolate chip cake dough with or without chocolate chips. The outer dough 32 would also be a chocolate chip cake dough, suitably dissimilar to the inner dough, and would, according to the present invention, contain chocolate chips. The chocolate chip cakes would be made by the apparatus and method according to the present invention described hereinbefore. Suitably, the inner dough would contain a humectant to provide the finished product with a moist and soft inner structure after baking.

The chocolate chips, i.e., the finely divided substance 26 in the outer dough mass 32, may have a size which provides from about 1500 chips per pound (0.45 kg) to about 10,000 chips per pound (0.45 kg). A favorable chip size is from about 4600 chips per pound (0.45 kg) to about 5000 chips per pound (0.45 kg), with about 4800 chips per pound (0.45 kg) being a particularly desirable chip size. The concentration of the chocolate chips in the outer dough 32 at the exit passage 28 may be from about 3 to about 40 weight percent based on the dough, and is suitably from about 7 to about 20 weight percent. A concentration of the chocolate chips of about 15 weight percent based on the dough has been found to be useful. The specific embodiments described hereinbefore are particularly useful for making chocolate chip cakes. The inner batter may or may not include the preparation of chocolate chip cakes. Satisfactory cakes can be made without chocolate chips in the inner batter.

The chocolate chip cake product prepared according to the above-described process has chocolate chips distributed throughout and penetrating the entire outer surface of the cake without the presence of an unsightly or invisible thin layer of baked dough crust covering the chocolate chips. The chocolate chip cake prepared according to the above-described process has a commercially desirable handmade appearance even though it is prepared by an automated, continuous manufacturing process.

In comparison, chocolate chip cakes with unequal outer and inner proportions prepared using conventional food extrusion processes and equipment will not have chocolate chips protruding from the outer surface of the outer dough and uncovered by a baked doughy layer.

Claims (15)

1. Apparatus (5) for coaxial extrusion to form a continuous food product (35) having unequal inner and outer portions (34,32), in which the inner portion (34) is encased in the outer portion (32) and the outer portion (32) is a dough containing finely divided material consisting of particles, the apparatus comprising: an inner extrusion opening (11) having an exit opening with a first cross-sectional area through which the inner portion (34) can be extruded; an outer extrusion opening (21) having an exit opening (25) with a second cross-sectional area that is larger than the first cross-sectional area; the inner extrusion opening (11) being recessed from the outer extrusion opening (21), the recessed distance (d) forming an exit passage (28) between the inner extrusion opening (11) and the outer extrusion opening (21); and wherein the outer extrusion orifice (21) has a generally annular bevel surface (24) for providing means (24) for substantially removing dough from the portions of particles passing through the outer surface (33) of the outer dough portion (32) which are oriented substantially parallel to the axis of the outer extrusion orifice (21), the bevel surface (24) terminating on the inside of the outer extrusion orifice (21) in a generally sharp cutting line (27) with the inner surface (22) of the outer extrusion orifice, the generally sharp cutting line (27) providing means (22,27) for introducing turbulence into the outer dough portion (32) which envelops the inner portion (34); first conduit means (31) communicating with the inner extrusion opening (11) for conveying the inner portion (34) thereto; and second conduit means (37) communicating with the outlet passage (28) for conveying the outer dough portion (32) thereto; characterized in that the arrangement is such that the finely divided material (26) in the outer dough portion (32) is rolled by the turbulence introducing means (22, 27) and a portion of at least a portion of the particles of the finely divided material (26) passes through the outer surface (33) of the outer dough portion (32) and the distance (d) is suitably adapted such that the particles of the finely divided material contained in the dough of the outer portion can pass through the exit passage (28) during operation of the device (5); and arcuate cutouts (37) are provided on the phase surface (34) and are aligned substantially parallel to the axis of the outer extrusion opening (21). 2. Apparatus according to claim 1, wherein the exit opening of the inner extrusion opening (11) and the exit opening (25) of the outer extrusion opening (21) are substantially annular and the exit passage (28) between the inner extrusion opening (11) and the outer extrusion opening (21) is substantially annular. 3. The apparatus of claim 1, wherein the bevel surface (24) has a length parallel to the axis of the outer extrusion opening (21) of about 1/16 inch (1.6 mm) to 5/16 inch (7.9 mm). 4. The apparatus of claim 3, wherein the distance (d) by which the inner extrusion opening (11) is recessed from the outer extrusion opening (21) is at least about 5/16 inch (7.9 mm) to about 7/16 inch (11.1 mm). 5. Apparatus according to any preceding claim, wherein the inner surface (22) of the outer extrusion opening (21) is a substantially annular, bevelled surface. 6. A method of coaxial extrusion to form a continuous food product (35) having unequal inner and outer portions (34,32), the inner portion (34) being enveloped in intimate contact by the outer portion (32) and the outer portion (32) being a dough material, the method comprising: Providing finely divided material (26) consisting of particles in the outer portion of dough material (32); Extruding the inner portion (34) through an inner extrusion opening (11); Passing the outer portion of dough material (32) containing finely divided material (26) through an exit passage (28) formed by deepening the inner extrusion opening (11) by a distance (d) from an outer extrusion opening (21), the distance (d) being sufficient to allow the particles of finely divided material (26) contained in the outer portion of dough material (32) to pass through the exit passage (28), wherein the outer portion of dough material (32) envelops the inner portion (34); passing the inner portion (34) encased by the outer portion of dough material (32) through the outer extrusion opening (21), thereby forming a composite, strand-like food product (35) having the outer portion of dough material (32) in intimate contact with the inner portion (34); creating turbulence in the outer portion of dough material (32) which surrounds the inner portion (34) causing at least a portion of the particles to roll and partially pass through the outer surface (33) of the outer portion of dough material (32) before the composite strand-like food product (35) exits the outer extrusion opening (21); and Removing dough from the portion of the particles which passes through the outer surface (33) of the outer portion of dough material (32) before the composite, strand-like food product (35) exits the outer extrusion opening (21). 7. A method according to claim 6, wherein the turbulence is generated by turbulence inducing means (22, 27) on the outer extrusion opening (21). 8. A method according to claim 6 or 7, wherein the dough is removed by providing the outer extrusion opening (21) with a bevel surface (24) which is substantially parallel to the axis of the outer extrusion opening (21). 9. The method of claim 8, wherein the turbulence is provided by the bevel surface (24) terminating in a generally smooth cutting line (27) on the inside of the outer extrusion orifice (21). 10. The method of claim 9, wherein the strand-like food product (35) which has passed through the outer extrusion opening (21) is deposited on a continuously moving horizontally disposed conveyor (30) running at a speed substantially equal to or just slightly faster than the extrusion speed, whereby the assembled strand-like food product (35) is aligned in a substantially straight line in the direction of travel of the conveyor (30) in the absence of discontinuities formed in the outer portion (32). 11. The method of claim 6, wherein the inner portion (34) is a dough material. 12. The method of claim 6 or 7, wherein the distance (d) is at least about 1.25 times the maximum dimension of the largest particle of the finely divided material (26). 13. The method of claim 6 or 12, wherein the outer portion (32) is a cake batter with chocolate chips, the finely divided material (26) is chocolate chips and the inner portion (34) is a cake batter with chocolate chips. 14. The method of claim 13, wherein the size of the chocolate chips is in the range of 1,500 chips per pound (0.45 kg) to 10,000 chips/pound (0.45 kg). 15. The method of claim 14, wherein the concentration of chocolate chips is about 3 to 40% by weight of the outer portion of dough (32).